Venezuela has calculated carboniferous reserves of more than 9,264 million metric tons. In addition, residues and coke are produced with the up-grading or refining of heavy oil. Basically, four qualities of coke exist: coke from petroleum combustion (pet-coke), regular coke, needle coke and recarburation coke.
The types of coke that are most valuable are recarburation cokes (used in steel industry) and needle cokes; whereas the least valuable is pet-coke since it has a low quality. Pet-coke is the one produced in greatest quantities worldwide, and is mainly used in thermal power stations and in the cement industry. Nevertheless, the demand for pet-coke from traditional consumers has decreased, therefore making it necessary to develop technology for non-conventional use/up-grading of pet-coke.
Gasification is an alternative for improvement of petroleum coke and mineral coal. The gasification of any organic material produces a synthesis gas, composed in its majority of carbon monoxide and hydrogen. Gasification technology has been available from the last century, mainly to process coal. The synthesis gas obtained by means of gasification can be used as raw material for production of alcohol, ammonia and synthetic liquid fuel. Also it can be used like fuel in a process for generation of electrical energy. The advantages to use coal as raw matter for production of synthesis gas or hydrogen are low cost, availability, and chemical stability. Nevertheless, gasification of coal has some disadvantages including high process temperature and pressure, consumption of oxygen, great amounts of toxic gas discharge and ash that requires the purification of products in separation units.
Recently, interest has resurged for a process that uses fuels such as coal or coke for synthesis gas and/or hydrogen generation and that does not require severe conditions of operation. An alternative process for the production of synthesis gas and/or hydrogen is a method for electro-gasification of pet-coke.
In the electro-gasification of pet-coke, two processes take place in parallel, namely, (i) synthesis gas and/or hydrogen production and (ii) recovery of metal from the carbon material. The advantage of this process is that the fraction of produced CO, CO2 and H2 can be changed with applied potential. Additionally, the gases produced in these reactions are pure and they do not require a later treatment. The electrochemical gasification according to the invention takes place at low temperatures, with a moderate potential with respect to electrolysis of the water and to atmospheric pressure, unlike the process of traditional gasification as used in refineries and that require temperatures above 800° C. and high pressures. An improved electro-gasification of pet-coke according to the invention has been shown to be an innovative process for the conversion of coke at low to moderate conditions of operation with impact potentials in: (i) reduction of coke volumes, (ii) generation of products of added value and (iii) recovery of metals. An important aspect of this technology is that the pet-coke slurries have low reaction rates due to some their properties such as low porosity and presence of some organic adsorbents. Therefore, a method is provided for pretreatment of the pet-coke to optimize size of particle and textural properties of pet-coke. Other objects and advantages will appear herein.